function Snake(el) {
    this.el = el
    this.len = 20
    this.snakeObj = [
      { x: 3, y :2, color:'red', el:null}, 
      { x: 2, y :2, color:'blue', el:null},
      { x: 1, y :2, color:'blue', el:null} 
    ]
    this.direction = 'right'
    this.kaishi()
}
Snake.prototype.kaishi=function(){
    this.remove()
    this.create()
    this.move()
}
Snake.prototype.remove = function() {
    for (let i = 0; i<this.snakeObj.length; i++) 
    {
        if (this.snakeObj[i].el)
        {
            this.el.removeChild(this.snakeObj[i].el)
        }
    }
}

Snake.prototype.create = function() 
{
    this.remove()
    for (let i = 0; i<this.snakeObj.length; i++) 
    {
        let divObj = document.createElement('div')
        divObj.style.borderRadius='50% 50%'
        divObj.style.width = this.len + 'px'
        divObj.style.height = this.len + 'px'
        divObj.style.position = 'absolute'
        divObj.style.left =  this.snakeObj[i].x*this.len+'px'
        divObj.style.top =  this.snakeObj[i].y *this.len+'px'
        divObj.style.background = this.snakeObj[i].color
        this.snakeObj[i].el = divObj
        this.el.appendChild(divObj)
        
    }
}
Snake.prototype.move = function() {
    for (let i = this.snakeObj.length - 1; i>0; i--) {
        this.snakeObj[i].x = this.snakeObj[i-1].x
        this.snakeObj[i].y = this.snakeObj[i-1].y
    }
    switch (this.direction) {
        case 'top':
            this.snakeObj[0].y -= 1
            break;
        case 'bottom':
            this.snakeObj[0].y += 1
            break;
        case 'left':
            this.snakeObj[0].x -= 1
            break;
        case 'right':
            this.snakeObj[0].x += 1
            break;
    }
    this.create()
}